Well, for starters, a little primer usually doesn't hurt.
The other thing I can think of, Hobby Boss has a history of using mold release.
This is usually a silicone spray. So, washing your parts prior to assembly is also a good idea. Just get a bucket of warm water and add a little Dawn (degreasing) dishwashing soap. Scrub gently then rinse and pat dry.
BTW, several years ago someone posted pictures of Akulas or Sierras being transported from Kamchatka and they had the dark gray anti-fouling paint.
I used either Tamiya's NATO Black or German Dark Gray to get that look.